-- sq x returns the square of x
sq :: Integer -> Integer
sq x = x * x

-- absolute x returns the absolute value of x
absolute :: Integer -> Integer
absolute x | x >= 0 = x
absolute x | x < 0  = -x

-- (alternative solution)
absolute' :: Integer -> Integer
absolute' x | x >= 0 = x
            | x < 0  = -x

-- power x n returns x to the power n
power :: Integer -> Integer -> Integer
power x 0         = 1
power x n | n > 0 = x * power x (n-1)

-- regions n computes the number of regions formed by n lines
regions :: Integer -> Integer
regions 0         = 1
regions n | n > 0 = regions (n-1) + n